[PATCH 3/3] perf/x86/mbm: Fix mbm counting during RMID recycling

[Vikas Shivappa]

Continuing from the previous patch, this handles the recycling part of
the counting.

When an event loses RMID we need to update the event->count
with total bytes till now and when an event gets a new RMID we need to
update the event->prev_count to zero bytes as we start new counting.

Signed-off-by: Vikas Shivappa <vikas.shiva...@linux.intel.com>
---
 arch/x86/events/intel/cqm.c | 39 ++++++++++++++++++++++++++++++++-------
 1 file changed, 32 insertions(+), 7 deletions(-)

diff --git a/arch/x86/events/intel/cqm.c b/arch/x86/events/intel/cqm.c
index a98d841..f91a172 100644
--- a/arch/x86/events/intel/cqm.c
+++ b/arch/x86/events/intel/cqm.c
@@ -487,6 +487,14 @@ static void update_mbm_count(u64 val, struct perf_event 
*event)
        local64_set(&event->hw.cqm_prev_count, val);
 }
 
+static inline void
+mbm_init_rccount(u32 rmid, struct perf_event *event, bool mbm_bytes_init)
+{
+       if (!mbm_bytes_init)
+               init_mbm_sample(rmid, event->attr.config);
+       local64_set(&event->hw.cqm_prev_count, 0UL);
+}
+
 /*
  * Exchange the RMID of a group of events.
  */
@@ -495,18 +503,26 @@ static u32 intel_cqm_xchg_rmid(struct perf_event *group, 
u32 rmid)
        struct perf_event *event;
        struct list_head *head = &group->hw.cqm_group_entry;
        u32 old_rmid = group->hw.cqm_rmid, evttype;
+       bool mbm_bytes_init = false;
        struct rmid_read rr;
+       u64 val;
 
        lockdep_assert_held(&cache_mutex);
 
        /*
         * If our RMID is being deallocated, perform a read now.
+        * For mbm, we need to store the bytes that were counted till now
         */
        if (__rmid_valid(old_rmid) && !__rmid_valid(rmid)) {
 
                rr = __init_rr(old_rmid, group->attr.config, 0);
                cqm_mask_call(&rr);
-               local64_set(&group->count, atomic64_read(&rr.value));
+
+               if (is_mbm_event(group->attr.config))
+                       update_mbm_count(atomic64_read(&rr.value), group);
+               else
+                       local64_set(&group->count, atomic64_read(&rr.value));
+
                list_for_each_entry(event, head, hw.cqm_group_entry) {
                        if (event->hw.is_group_event) {
 
@@ -514,8 +530,12 @@ static u32 intel_cqm_xchg_rmid(struct perf_event *group, 
u32 rmid)
                                rr = __init_rr(old_rmid, evttype, 0);
 
                                cqm_mask_call(&rr);
-                               local64_set(&event->count,
-                                           atomic64_read(&rr.value));
+                               val = atomic64_read(&rr.value);
+                               if (is_mbm_event(event->attr.config))
+                                       update_mbm_count(val, event);
+                               else
+                                       local64_set(&event->count,
+                                                   atomic64_read(&rr.value));
                        }
                }
        }
@@ -535,12 +555,17 @@ static u32 intel_cqm_xchg_rmid(struct perf_event *group, 
u32 rmid)
         */
        if (__rmid_valid(rmid)) {
                event = group;
-               if (is_mbm_event(event->attr.config))
-                       init_mbm_sample(rmid, event->attr.config);
+
+               if (is_mbm_event(event->attr.config)) {
+                       mbm_init_rccount(rmid, event, mbm_bytes_init);
+                       mbm_bytes_init = true;
+               }
 
                list_for_each_entry(event, head, hw.cqm_group_entry) {
-                       if (is_mbm_event(event->attr.config))
-                               init_mbm_sample(rmid, event->attr.config);
+                       if (is_mbm_event(event->attr.config)) {
+                               mbm_init_rccount(rmid, event, mbm_bytes_init);
+                               mbm_bytes_init = true;
+                       }
                }
        }
 
-- 
1.9.1